Flash memory-based solid stated drives (SSDs) have been adopted in data centers primarily because of their superior I/O characteristics compared to Serial AT Attachment (SATA)-based SSDs. However, flash-based SSDs suffer from write amplification caused by the erase-before-rewrite limitation, and background garbage collection and wear levelling required for the flash memory. A write amplification factor (WAF) is defined as a ratio of physical writes to logical writes. Since SSDs have limited write (erase) cycles, a higher WAF shortens the device lifetime of the SSDs, and thus increases the cost of ownership of the datacenter. In addition, the lifetime, and hence the total cost of ownership (TCO) of the datacenter, is affected by the workloads running on the SSDs.
Existing WAF models for determining a WAF for SSDs primarily utilize the architectural characteristics of the SSD, garbage collection policies, and distribution of workloads (uniform or non-uniform) as factors. However, these WAF models do not consider the effects of workload sequentiality on WAF that may affect the workloads running on the SSDs, and hence the ultimate TCO.